U.S. patent application number 11/771633 was filed with the patent office on 2008-03-06 for interchangeable container.
This patent application is currently assigned to ProMetal RCT GmbH. Invention is credited to Rainer Hochsmann, Stefan Huhn, Udo Marschner, Alexander Muller, Uli Schrupp, Martin Stachulla.
Application Number | 20080053998 11/771633 |
Document ID | / |
Family ID | 38617319 |
Filed Date | 2008-03-06 |
United States Patent
Application |
20080053998 |
Kind Code |
A1 |
Hochsmann; Rainer ; et
al. |
March 6, 2008 |
Interchangeable Container
Abstract
An interchangeable container (10) for a system for building a
mold body by forming superimposed layers of granular material, the
granular material locally and selectively hardened layer by layer,
the container including a bottom structure (14) that is
displaceable in the interior of the container in a direction in
parallel with the container side walls, the container further
including at least one spindle drive comprising a vertical screw
spindle (20) which is rotatably mounted in a container side of the
container (10), and a spindle screw nut (22) on which the bottom
structure (14) is supported, such that the bottom structure can be
lowered step by step in the interior of the container by means of
the spindle drive.
Inventors: |
Hochsmann; Rainer;
(Genderkingen, DE) ; Muller; Alexander;
(Konigsbrunn, DE) ; Schrupp; Uli; (Diedorf,
DE) ; Huhn; Stefan; (Augsburg, DE) ;
Marschner; Udo; (Biburg, DE) ; Stachulla; Martin;
(Augsburg, DE) |
Correspondence
Address: |
CAHN & SAMUELS LLP
1100 17th STREET NW
SUITE 401
WASHINGTON
DC
20036
US
|
Assignee: |
ProMetal RCT GmbH
Augsburg
DE
|
Family ID: |
38617319 |
Appl. No.: |
11/771633 |
Filed: |
June 29, 2007 |
Current U.S.
Class: |
220/287 |
Current CPC
Class: |
B29C 64/153 20170801;
B33Y 40/00 20141201 |
Class at
Publication: |
220/287 |
International
Class: |
B65D 51/00 20060101
B65D051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 4, 2006 |
DE |
202006010327.9 |
Claims
1. An interchangeable container for a system for building a mold
body by forming superimposed layers of granular material, the
granular material locally and selectively hardened layer by layer,
the container comprising: at least one pair of side walls; a bottom
structure that is displaceable in the interior of the container in
a direction in parallel with said side walls; and at least one
spindle drive comprising a vertical screw spindle which is
rotatably mounted in a container side of the container, and a
spindle screw nut on which the bottom structure is supported, such
that the bottom structure can be lowered step by step in the
interior of the container by means of the spindle drive.
2. The Interchangeable container according to claim 1, wherein the
screw spindle further comprises a drive clutch for detachably
coupling with a stationary stepping motor.
3. The interchangeable container according to claim 2, wherein a
curtain is attached to the bottom structure along the container
side on which the screw spindle is arranged, the curtain deviated
by means of rolls on a upper side of the container and adjustably
drawn down in correspondence with the lowering motion of the bottom
structure.
4. The interchangeable container according to claim 1, wherein in a
lower container portion, preferably in the container side
comprising the screw spindle, a stepping motor is integrated into
the container, the stepping motor being coupled by means of a
transmission member with the screw spindle.
5. The interchangeable container according to claim 4, wherein a
curtain is attached to the bottom structure along the container
side on which the screw spindle is arranged, the curtain deviated
by means of rolls on a upper side of the container and adjustably
drawn down in correspondence with the lowering motion of the bottom
structure.
6. The interchangeable container according to claim 1, wherein a
curtain is attached to the bottom structure along the container
side on which the screw spindle is arranged, the curtain deviated
by means of rolls on a upper side of the container and adjustably
drawn down in correspondence with the lowering motion of the bottom
structure.
Description
[0001] This patent application claims priority under 35 U.S.C.
.sctn.119 to German patent application number 20 2006 010 327.9
filed on Jul. 4, 2006, which is hereby incorporated by
reference.
I. FIELD OF THE PRESENT INVENTION
[0002] The invention relates to an interchangeable mobile container
for a system for building a mold body by forming superimposed
layers of granular material.
II. BACKGROUND OF THE INVENTION
[0003] In prior art, systems and methods are known in the field of
rapid prototyping and laser sintering, wherein a granular material
is deposited in separate layers on a platform in a container, and
is hardened locally and selectively layer by layer, so as to build
up a solidified mold body from the granular material. For doing so,
the bottom of the container, which is formed by the platform and
which is height-adjustable, is lowered by one layer thickness
respectively before application of a new layer. Once all necessary
layers are applied and selectively hardened, the mold body formed
in this manner may be removed, for example in a removal station, by
removing the non-solidified granular material.
[0004] A removable or interchangeable container in which a mold
body can be built in this manner is for example known from EP
1037739 B1. The interchangeable container disclosed therein
comprises a container bottom forming a workpiece platform that can
be moved vertically within the container. The interchangeable
container comprises engagement recesses in a rear side wall,
through which one or more support arms reach underneath the
workpiece platform, the support arms being height-adjustably
mounted to the building station of the system. As soon as the
forming of a mold body is complete, the workpiece platform is
locked and the whole interchangeable container including the mold
body can be removed from the building station of the system.
[0005] Alternatively, a lifting device may be integrated in the
interchangeable container under the workpiece platform according to
cited prior art for the height-adjustability of the same.
[0006] However, interchangeable containers designed in this manner
have the disadvantage that they have to comprise sufficiently large
and long engagement recesses in the embodiment without an
integrated lifting device, in order that the support arms at the
building station of the system can engage therethrough. In
addition, locking devices are required, in order to allow the
workpiece platform to remain at an unchanged level when the
interchangeable container is removed from the building station,
wherein then the support arms are not disposed underneath the
workpiece platform anymore. On the other hand, the interchangeable
container comprising a lifting device integrated under the
workpiece platform is very complex, whereby the interchangeable
container becomes large and heavy and is therefore difficult to
handle when changing or moving from one station to another.
III. SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide an
interchangeable container which is easy to handle and the
height-adjustable workpiece platform of which can be operated in an
easy and reliable manner.
[0008] According to the present invention, an interchangeable
container is provided for a system for building a mold body by
forming superimposed layers of granular material, the granular
material locally and selectively hardened layer by layer, the
container including a bottom structure that is displaceable in the
interior of the container in a direction in parallel with the
container side walls, the container further including at least one
spindle drive comprising a vertical screw spindle which is
rotatably mounted in a container side of the container, and a
spindle screw nut on which the moveable bottom structure is
supported, such that the bottom structure can be lowered step by
step in the interior of the container by means of a spindle drive
which is directly integrated into a side wall of the container.
[0009] In an embodiment of the present invention, the screw spindle
further comprises a drive clutch at the lower spindle end for
detachably coupling with a stationary stepping motor.
[0010] Alternatively, a stepping motor can be directly integrated
into the container, wherein the stepping motor is coupled by means
of a transmission member with the screw spindle.
IV. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention will be explained on the following pages on
the basis of preferred embodiments with reference to the figures of
the drawings, wherein:
[0012] FIG. 1a is a sectional lateral view of an interchangeable
container according to a first embodiment of the invention;
[0013] FIG. 1b is schematic partial view of an interchangeable
container according to the first embodiment;
[0014] FIG. 2 is a perspective view of an interchangeable container
according to a second embodiment of the invention;
[0015] FIG. 3 is a perspective view of an interchangeable container
according to a third embodiment of the invention.
V. DETAILED DESCRIPTION OF THE INVENTION
[0016] According to the first embodiment, which is shown in a
sectional lateral view of FIG. 1a and in a partial view of FIG. 1b,
the interchangeable container 10 according to the invention is
formed as a mobile container which is substantially rectangular and
has four side walls and is open on the top side.
[0017] Although the interchangeable container 10 may have a square
cross-section, the interchangeable container preferably has an
elongated rectangular cross-section, which is limited by two
horizontally long sidewalls and two horizontally short side walls,
which are each arranged so as to face each other in pairs. One of
the side walls, which in this case is one of the short side walls,
comprises engagement recesses 16 being formed like vertical slots.
Support projections of a bottom structure 14 which is
height-adjustable in the container reach through the engagement
recesses 16, on which bottom structure a workpiece platform 12
forming the bottom of the container is supported in the interior of
the container, and which itself is supported on a lifting device
which is provided on the outer surface of the short side wall of
the container 10. The bottom structure 14 may be designed in the
form of support arms or in the form of a support frame or the
like.
[0018] The lifting device comprises a spindle drive or ball-screw
actuator, wherein the spindle screw nut 22 which is adjusted along
the screw spindle 20 by turning the same, is provided as
circulating ball screw nut. The spindle 20 is arranged vertically
and is preferably pivoted at the top and at the bottom. The spindle
screw nut 22 is firmly connected to the bottom structure 14, and by
a movement of the spindle screw nut 22 along the spindle 20, a
height-adjustability of the bottom structure 14 and thereby of the
workpiece platform 12 is provided. In addition, the spindle drive
may be self-locking, such that no support of the workpiece platform
12 is necessary when removing the interchangeable container 10 from
a station.
[0019] Furthermore, at one end of the spindle 20, preferably at the
lower end thereof, a clutch 24 is provided for coupling to a motor
30. The motor 30 for powering the spindle 20 is preferably an
electrical direct current servo motor or stepping motor which in
this first embodiment is provided stationarily at the building
station of the rapid prototyping system. As soon as the
interchangeable container is inserted into the building station of
the system, the driven shaft of the motor 30 disposed in the
building station is engaged in a preferably self-acting manner with
the clutch 24 of the spindle 20 via a transmission member, so as to
easily ensure a gradual lowering of the workpiece platform in the
building station for applying separate layers of the granular
material.
[0020] As shown in FIG. 1b, the transmission member can be a
coupling member 34 on the driven shaft of the motor 30 being
stationary in this case, which has positive fit with the clutch 24
at the spindle 20. The coupling member 34 can be displaced axially
on the driven shaft of the motor 30 and can be engaged or
disengaged with the clutch 24 at the spindle 20 by means of a
displacing device 32.
[0021] The transmission member for transmitting motor power to the
clutch 24 and thereby to the spindle 20 may for example also
comprise a belt drive, in particular a cogged belt drive or chain.
Transmission of the motor power to the spindle may also take place
by means of a gear transmission or by means of coupling disks.
[0022] In one alternative of the first embodiment of the invention,
the interchangeable container comprises in each of the two short
side walls a lifting device in the form of a spindle drive. This
means that engagement recesses 16 are provided on two sides of the
container 10 facing each other, through which the support
projections of the bottom structure 14 reach, on which the
workpiece platform 12 is supported. At the outer surface of the
container 10, the support projections of the bottom structure 14
are connected at their respective ends to a spindle screw nut 22
which is arranged to be moved on a vertically arranged spindle 20.
Every lifting device is provided with at least one spindle 20,
which is preferably arranged in the lateral center of the container
side. In order to allow a simultaneous and synchronous motion of
the spindles 20 and thus a homogeneous lowering of the workpiece
platform 12 when building the mold body, the two spindles may be
coupled to each other underneath the container, for example by
means of a toothed belt, whereby for both lifting devices one joint
motor can be provided, wherein one of the spindles can be provided
with a clutch 24 for coupling to a coupling 34 of a stationary
motor 30 in addition to the toothed belt, as explained on the basis
of FIG. 1b. In the building station there can also be a second
motor which is coupled to the second spindle, wherein the two
motors are controlled to be synchronized with each other.
[0023] Optionally, recesses 18 may be provided in the lower edges
of the long side walls of the interchangeable container 18, through
which for example a forklift truck can reach with its fork, so as
to move the interchangeable container into a station of the system
or out of the same.
[0024] According to the second embodiment of the present invention,
which is shown in FIG. 2, the interchangeable container 10 which is
substantially equal to the interchangeable container according to
the first embodiment comprises a stepping motor 30 which is mounted
to the side wall where the ball-screw actuator 20 is located, such
that a lifting device including a stepping motor is integrated in
at least one side of the interchangeable container. As shown in
FIG. 2, the stepping motor 30 may be located next to the spindle 20
at a corner of the container. In this embodiment, transmission of
the motor power to the spindle is ensured by means of a toothed
belt 32. The energy for the motor 30 may be provided by an
accumulator directly at the interchangeable container 10, or plug
contacts may be provided which act together with corresponding plug
contacts at the building station or another station of the system,
in order to provide the motor 30 with power or energy.
[0025] Also in this embodiment, the interchangeable container may
comprise a neck spindle 20 on each container side facing each
other, wherein only one drive motor is provided which is coupled to
one of the spindles 20, which on their part are coupled to each
other, or wherein one drive motor 30 is provided per spindle 20 and
these drive motors are concurrently synchronized with each
other.
[0026] In the first embodiment as well as in the second embodiment,
the engagement recesses are closed by means of brush sealings, band
sealings or the like, at least above the workpiece platform in each
of the height-adjusting positions of the same, in order to prevent
the granular material from coming out on the side. For example, a
corrugated tube might be provided at the spindle as additional
protection.
[0027] According to the third embodiment of the invention, which is
shown in FIG. 3, the interchangeable container 10, which
incidentally is substantially equal to the third and second
embodiment, respectively, is designed without having a side wall on
the side comprising the spindle. Instead, a curtain 40 is provided.
The curtain 40 serves for sealing the open side of the container at
least above the workpiece platform, in order to prevent granular or
powdery material from pouring out of the container 10 on the side.
The curtain 40 extends over the entire width of the short side of
the container, such that in this embodiment the side wall may be
omitted entirely. The curtain 40 is attached to the lateral edge of
the workpiece platform 12 and extends from this edge along the
inner surface up to the upper edge of the container, is diverted
outside by guide rolls at the upper edge, and can be guided
downwards again at the outer side of the interchangeable container
10. Alternatively, the curtain may be rolled up. In order to ensure
a continuous guiding of the curtain 40 when lowering the workpiece
platform 12, the curtain may be kept under stress and guided at the
same time at its end which is disposed outside the interchangeable
container 10 by means of a suitable device. Such a suitable device
may comprise extension springs or a wire or a cord which is winded
up or down under stress. The curtain itself particularly consists
of a steel band or a band made of fiber-reinforced synthetic
material, such that it is on the one hand flexible enough to be
guided at the upper edge of the interchangeable container, and on
the other hand strong enough to resist the load acting laterally on
the curtain due to the granular material on the inner side of the
container.
[0028] It should be noted that the second or third embodiment may
also comprise two spindle drives which are arranged as described
with regard to the alternative of the first embodiment.
[0029] Although it is not shown in the figures, there might also be
an embodiment of the interchangeable container being entirely or in
part open on each side comprising a spindle 20, without the curtain
40 according to the third embodiment or sealings for engagement
recesses according to the first or second embodiment being
provided. In such embodiments the layered body built in the
interchangeable container on the building platform may be provided
with an artificial wall which is built by selectively hardening the
granular material layer by layer along the open side of the
container or at least along the engagement recesses.
* * * * *